Querying data from a table

Author: learning-zone

mysql-queries.md

@@ -16,3 +16,29 @@
 |  09. |LEFT JOIN |Returns all rows from the ‘left’ (1st) table with the matching rows in the right (2nd)|
 |  10. |RIGHT JOIN|Returns all rows from the ‘right’ (2nd) table with the matching rows in the left (1st)|
 |  11. |FULL OUTER JOIN|Returns rows that match either in the left or right table|
+
+
+#### Reporting Aggregate functions
+
+In database management, an aggregate function is a function where the values of multiples rows are grouped to form a single value. 
+
+|Sl.No |Function   | Description                                       |
+|------|-----------|---------------------------------------------------|
+|  01. |COUNT	   |Return the number of rows in a certain table/view  |
+|  02. |SUM	   |Accumulate the values|
+|  03. |AVG	   |Returns the average for a group of values|
+|  04. |MIN	   |Returns the smallest value of the group|
+|  05. |MAX	   |Returns the largest value of the group|
+
+
+#### Querying data from a table
+
+|Sl.No |Query            | Description                                       |
+|------|-----------------|---------------------------------------------------|
+| 01.  |SELECT c1 FROM t |Select data in column c1 from a table named t      |
+| 02.  |SELECT * FROM t	 |Select all rows and columns from a table named t   |
+| 03.  |SELECT c1 FROM t WHERE c1 = ‘test’|Select data in column c1 from a table named t where the value in c1 = ‘test’
+| 05.  |SELECT c1 FROM t ORDER BY c1 ASC (DESC)|Select data in column c1 from a table name t and order by c1, either in ascending (default) or descending order |
+| 07.  |SELECT c1 FROM t ORDER BY c1LIMIT n OFFSET offset|Select data in column c1 from a table named t and skip offset of rows and return the next n rows|
+| 08.  |SELECT c1, aggregate(c2) FROM t GROUP BY c1|Select data in column c1 from a table named t and group rows using an aggregate function |
+| 09.  |SELECT c1, aggregate(c2) FROM t GROUP BY c1 HAVING condition|Select data in column c1 from a table named t and group rows using an aggregate function and filter these groups using ‘HAVING’ clause|